Full length alpha-synuclein is present in cerebrospinal fluid from Parkinson's disease and normal subjects

Several clues suggest that alpha-synuclein, a presynaptic protein, plays a central role in the pathogenesis of idiopathic Parkinson's disease (PD). To search a peripheral marker of PD, we analyzed presence and amount of alpha-synuclein in CSF from 12 PD patients and 10 neurologically normal subjects. The protein was extracted from CSF samples through immunoprecipitation and immunoblotting with different specific anti-alpha-synuclein antibodies. We identified a 19 kDa band that corresponds to monomeric alpha-synuclein, given its comigration with homologue human recombinant peptide as well as with the protein extracted from cerebral cortex of normal subjects. The amount of CSF 19 kDa alpha-synuclein did not significantly vary in PD and normal cases. These findings have two implications: (a) full length alpha-synuclein is released by neurons in the extracellular space; (b) alpha-synuclein does not appear a peripheral marker of PD pathology.

3D niche microarrays for systems-level analyses of cell fate

The behaviour of mammalian cells in a tissue is governed by the three-dimensional (3D) microenvironment and involves a dynamic interplay between biochemical and mechanical signals provided by the extracellular matrix (ECM), cell-cell interactions and soluble factors. The complexity of the microenvironment and the context-dependent cell responses that arise from these interactions have posed a major challenge to understanding the underlying regulatory mechanisms. Here we develop an experimental paradigm to dissect the role of various interacting factors by simultaneously synthesizing more than 1,000 unique microenvironments with robotic nanolitre liquid-dispensing technology and by probing their effects on cell fate. Using this novel 3D microarray platform, we assess the combined effects of matrix elasticity, proteolytic degradability and three distinct classes of signalling proteins on mouse embryonic stem cells, unveiling a comprehensive map of interactions involved in regulating self-renewal. This approach is broadly applicable to gain a systems-level understanding of multifactorial 3D cell-matrix interactions.

Neurotrophins rescue cerebellar granule neurons from oxidative stress-mediated apoptotic death: selective involvement of phosphatidylinositol 3-kinase and the mitogen-activated protein kinase pathway

Cerebellar granule neurons maintained in medium containing serum and 25 mM K+ reliably undergo an apoptotic death when switched to serum-free medium with 5 mM K+. New mRNA and protein synthesis and formation of reactive oxygen intermediates are required steps in K+ deprivation-induced apoptosis of these neurons. Here we show that neurotrophins, members of the nerve growth factor gene family, protect from K+/serum deprivation-induced apoptotic death of cerebellar granule neurons in a temporally distinct manner. Switching granule neurons, on day in vitro (DIV) 4, 10, 20, 30, or 40, from high-K+ to low-K+/serum-free medium decreased viability by >50% when measured after 30 h. Treatment of low-K+ granule neurons at DIV 4 with nerve growth factor, brain-derived neurotrophic factor (BDNF), neurotrophin-3, or neurotrophin-4/5 (NT-4/5) demonstrated concentration-dependent (1-100 ng/ml) protective effects only for BDNF and NT-4/5. Between DIV 10 and 20, K+-deprived granule neurons showed decreasing sensitivity to BDNF and no response to NT-4/5. Cerebellar granule neuron death induced by K+ withdrawal at DIV 30 and 40 was blocked only by neurotrophin-3. BDNF and NT-4/5 also circumvented glutamate-induced oxidative death in DIV 1-2 granule neurons. Granule neuron death caused by K+ withdrawal or glutamate-triggered oxidative stress was, moreover, limited by free radical scavengers like melatonin. Neurotrophin-protective effects, but not those of antioxidants, were blocked by selective inhibitors of phosphatidylinositol 3-kinase or the mitogen-activated protein kinase pathway, depending on the nature of the oxidant stress. These observations indicate that the survival-promoting effects of neurotrophins for central neurons, whose cellular antioxidant defenses are challenged, require activation of distinct signal transduction pathways.

Headache and pregnancy: a systematic review

This systematic review summarizes the existing data on headache and pregnancy with a scope on clinical headache phenotypes, treatment of headaches in pregnancy and effects of headache medications on the child during pregnancy and breastfeeding, headache related complications, and diagnostics of headache in pregnancy. Headache during pregnancy can be both primary and secondary, and in the last case can be a symptom of a life-threatening condition. The most common secondary headaches are stroke, cerebral venous thrombosis, subarachnoid hemorrhage, pituitary tumor, choriocarcinoma, eclampsia, preeclampsia, idiopathic intracranial hypertension, and reversible cerebral vasoconstriction syndrome. Migraine is a risk factor for pregnancy complications, particularly vascular events. Data regarding other primary headache conditions are still scarce. Early diagnostics of the disease manifested by headache is important for mother and fetus life. It is especially important to identify “red flag symptoms” suggesting that headache is a symptom of a serious disease. In order to exclude a secondary headache additional studies can be necessary: electroencephalography, ultrasound of the vessels of the head and neck, brain MRI and MR angiography with contrast ophthalmoscopy and lumbar puncture. During pregnancy and breastfeeding the preferred therapeutic strategy for the treatment of primary headaches should always be a non-pharmacological one. Treatment should not be postponed as an undermanaged headache can lead to stress, sleep deprivation, depression and poor nutritional intake that in turn can have negative consequences for both mother and baby. Therefore, if non-pharmacological interventions seem inadequate, a well-considered choice should be made concerning the use of medication, taking into account all the benefits and possible risks.

Alterations of calcium metabolism and of parathyroid function in primary aldosteronism, and their reversal by spironolactone or by surgical removal of aldosterone-producing adenomas

In order to investigate the possible existence of abnormal calcium metabolism and parathyroid function in primary aldosteronism (PA), we have compared the calcium/parathyroid hormone (PTH) profile of patients with PA with the profile of healthy normotensive subjects and of patients with essential hypertension (EH). Furthermore, we have evaluated the effects of spironolactone and the surgical removal of aldosterone-producing adenomas on the calcium/PTH profile in the PA patients. Four groups of 10 subjects each participated in the study: 1) hypertensive patients with PA, 2) patients with low-renin EH (LREH), 3) patients with normal-renin EH (NREH), 4) normotensive healthy subjects (NS). The four groups were well-matched for age, sex, body mass index, and renal function. The three hypertensive groups were also matched closely for blood pressure values and for duration of hypertension. In all subjects, after 1 week of a controlled intake of Na and K, the following parameters were measured: urine excretion of Na, K, Ca, Mg, and P, plasma levels of K, Mg, inorganic P, total calcium and ionized calcium, and plasma renin activity, aldosterone concentration, and intact PTH. Blood pressure and laboratory parameters were determined again in all the PA patients after 1 month of 100 mg daily spironolactone administration, and in four out of the 10 PA patients 2 months after surgical removal of aldosterone-producing adenomas. All of these subjects had undergone the same controlled intake of Na and K indicated above. Serum intact PTH was higher in PA patients than in the other three groups (P < .01), and serum ionized calcium was significantly higher in normotensive subjects than in the three hypertensive groups (v PA P < .01, v LREH and v NREH P < .05). An increase in serum ionized calcium and a decrease in PTH level were associated with both spironolactone administration (P < .001) and surgical treatment (P < .05). These results suggest the presence of calcium metabolism alterations in both PA and EH patients, but that these alterations are more exaggerated in PA, so that higher PTH levels are needed for maintaining low-normal levels of serum ionized calcium.

Crystal structure and refolding properties of the mutant F99S/M153T/V163A of the green fluorescent protein

The mutant F99S/M153T/V163A of the Green Fluorescent Protein (c3-GFP) has spectral characteristics similar to the wild-type GFP, but it is 42-fold more fluorescent in vivo. Here, we report the crystal structure and the refolding properties of c3-GFP and compare them with those of the less fluorescent wt-GFP and S65T mutant. The topology and the overall structure of c3-GFP is similar to the wild-type GFP. The three mutated residues, Ser99, Thr153, and Ala163, lie on the surface of the protein in three different beta-strands. The side chains of Ser99 and Thr153 are exposed to the solvent, whereas that of Ala163 points toward the interior of the protein. No significant deviation from the structure of the wild-type molecule is found around these positions, and there is not clear evidence of any distortion in the position of the chromophore or of the surrounding residues induced by the mutated amino acids. In vitro refolding experiments on urea-denatured c3-GFP reveal a renaturation behavior similar to that of the S65T molecule, with kinetic constants of the same order of magnitude. We conclude that the higher fluorescence activity of c3-GFP can be attributed neither to particular structural features nor to a faster folding process, as previously proposed.

The metabolism and imaging in live cells of the bovine prion protein in its native form or carrying single amino acid substitutions

Prion diseases are probably caused by an abnormal form of a cellular glycoprotein, the prion protein. Recent evidence suggests that the prion strain causing BSE has been transmitted to humans, thereby provoking a variant form of Creutzfeldt-Jacob disease. In this work, we analyzed the behavior of normal and malformed isoforms of the bovine PrP in transfected mammalian cell lines. Biochemical and immunocytochemical assays were complimented with imaging of live cells expressing fusion constructs between PrP and GFP. Bovine homologues of human E200K and D178N (129M) mutations were used as models of pathogenic isoforms. We show that the GFP does not impair the metabolism of native and mutant bPrPs and is thus a valid marker of PrP cellular distribution. We also show that each amino acid replacement provokes alterations in the cell sorting and processing of bPrP. These are different from those ascribed to both murine mutant homologues. However, human and bovine PrPs carrying the D178N genotype had similar cellular behavior.

The use of reverse-phase high-performance liquid chromatography and precolumn derivatization with dansyl chloride for quantitation of specific amino acids in collagen and elastin

A rapid and accurate reverse-phase high-performance liquid chromatography procedure for amino acid analysis of connective tissue proteins has been optimized. The method is based on quantitative dansyl chloride precolumn derivatization of protein hydrolyzates and chromatographic separation of the dansyl derivatives on Ultrasphere ODS C18 column. High molar uv absorption of Pro and Hyp derivatives, quantitation of low Des and Ide amounts (60 pmol), and good separation of all the amino acid derivatives (CV mostly less than 0.1%) including Hyl overcome the difficulties of other methods in producing reliable single run amino acid analysis of collagen and elastin. The use of fluorescence detector and the possibility of concentrating derivatized samples would give even higher sensitivity to the system. The procedure appeared to be suitable for single run analysis of other proteins, particularly those having an unbalanced amino acid composition.

Brain-derived neurotrophic factor selectively rescues mesencephalic dopaminergic neurons from 2,4,5-trihydroxyphenylalanine-induced injury

Brain-derived neurotrophic factor (BDNF) supports the survival of sensory neurons as well as retinal ganglion cells, basal forebrain cholinergic neurons, and mesencephalic dopaminergic neurons in vitro. Here we examined the ability of BDNF to confer protection on cultured dopaminergic neurons against the neurotoxic effects of 6-hydroxyDOPA (TOPA or 2,4,5-trihydroxyphenylalanine), a metabolite of the dopamine pathway suggested to participate in the pathology of Parkinson's disease. Cells prepared from embryonic day 14-15 rat mesencephalon were maintained with 10-50 ng/ml BDNF for 7 days prior to addition of TOPA (10-30 microM) for 24 hr. In BDNF-treated cultures, the extensive loss (> 90%) of tyrosine hydroxylase immunopositive cells was virtually (< 10%) eliminated, while the equally drastic loss (> 90%) of the overall cell population was limited to only a 25-30% recovery. Furthermore, the monosialoganglioside GM1 (1-10 microM), although inactive alone, acted synergistically with subthreshold amounts of BDNF to rescue tyrosine hydroxylase-positive cells against TOPA neurotoxicity. These results add impetus to exploring the therapeutic potential of gangliosides and BDNF in Parkinson's disease.

KDC1, a novel carrot root hair K+ channel. Cloning, characterization, and expression in mammalian cells

Potassium is an essential nutrient which plays an important role in many aspects of plant growth and development. Plants have developed a number of highly specific mechanisms to take up potassium from the soil; these include the expression of K(+) transporters and potassium channels in root cells. Despite the fact that root epidermal and hair cells are in direct contact with the soil, the role of these tissues in K(+) uptake is not well understood. Here we report the molecular cloning and functional characterization of a novel potassium channel KDC1 which forms part of a new subfamily of plant K(in) channels. Kdc1 was isolated from carrot root RNA and in situ hybridization experiments show Kdc1 to be highly expressed in root hair cells. Expressing the KDC1 protein in Chinese hamster ovary cells identified it as a voltage and pH-dependent inwardly rectifying potassium channel. An electrophysiological analysis of carrot root hair protoplasts confirmed the biophysical properties of the Kdc1 gene product (KDC1) in the heterologous expression system. KDC1 thus represents a major K(+) uptake channel in carrot root hair cells.

Photochemical stroke and brain-derived neurotrophic factor (BDNF) mRNA expression

In situ hybridization and Northern blotting were used to study the expression of brain-derived neurotrophic factor (BDNF) mRNA in the rat brain following photochemical stroke. A focal thrombotic lesion of the sensorimotor cortex was produced by intravenously injecting the light-sensitive dye rose bengal and exposing the skull to a controlled beam of light. Four hours after the light exposure the level of BDNF mRNA was increased in the hippocampus and cortex ipsilateral and perifocal to the lesion. The stroke-induced BDNF mRNA increase was prevented by the non-competitive glutamate receptor blocker dizocilpine (MK-801). The results indicate that the activation of N-methyl-D-aspartate (NMDA)-sensitive glutamate receptors is involved in the stroke-triggered stimulation of BDNF mRNA increase.

Synthesis, purification, and characterization of human ciliary neuronotrophic factor from E. coli

The cDNA for human ciliary neuronotrophic factor (CNTF) has been cloned into an expression vector under the control of the T7 promoter. The BL21 strain of E. coli was transformed with this vector. Human CNTF accounted for about 30% of the total bacterial protein after induction with isopropyl-B-D-thiogalactopyranoside. This human CNTF was purified to homogeneity from inclusion bodies by a combination of ion exchange chromatography and reverse-phase high performance liquid chromatography. The amino-terminal amino acid sequence of the purified protein was identical to the deduced amino acid sequence; however, the methionyl residue has been removed. On SDS-PAGE gels, human CNTF displayed a molecular weight of about 24 kDa, in accord with its deduced molecular mass; a pI of 5.8 indicates the acidic nature of the molecule. A proposed structure for human CNTF includes major alpha helical regions. The ED50 of purified human CNTF was approximately 30 pM, using cultured embryonic day 10 chicken dorsal root ganglion neurons; no activity was observed with neurons from embryonic day 8 ganglia. Polyclonal antibodies prepared against both a synthetic peptide of CNTF and the entire human CNTF protein recognized a single 24 kDa band on Western blots, corresponding to human CNTF. However, only the antibodies against intact CNTF blocked its biological activity. This represents the first molecular expression and purification of human CNTF.

Susceptibility of the prion protein to enzymic phosphorylation

Ten protein kinases have been assayed for their ability to phosphorylate in vitro the recombinant bovine PrP (25-242) (rbPrP). Substantial phosphorylation was observed with PKC, CK2, and two tyrosine kinases, Lyn and c-Fgr. With regard to CK2, phosphorylation occurs at Ser 154 with a stoichiometry of about 0.1 mol phosphate/mol rbPrP, which is doubled by mild heat treatment of rbPrP. Heat also reduces the overall protein ellipticity, suggesting that reversibly unfolded conformers are more susceptible to phosphorylation. Our data disclose the possibility that phosphorylation might modulate PrP biological activity.

Increased plasma levels of platelet-derived growth factor (PDGF-BB + PDGF-AB) in patients with never-treated mild essential hypertension

Platelet-derived growth factor (PDGF) could play a role in both vascular hypertrophy and atherosclerotic disease associated with hypertension. To assess whether plasma PDGF level is increased in mild essential hypertension, we measured plasma PDGF concentration in 25 never-treated patients with uncomplicated mild essential hypertension and in 22 normotensive healthy subjects. To evaluate the contribution of platelets to plasma PDGF in the two groups, we also measured plasma beta-thromboglobulin (BTG). Measurement of PDGF was carried out through an enzyme-linked immunoadsorbent assay, which detects two PDGF dimers, namely PDGF-BB and PDGF-AB. Both plasma PDGF and BTG were higher in the hypertensive than in the normotensive subjects. The ratio of PDGF to BTG was similar in the two groups. Plasma PDGF was weakly correlated with plasma BTG in the normotensive subjects, whereas this relationship was lost in the hypertensive patients. Our results suggest that the increase in plasma PDGF (PDGF-AB + PDGF-BB) in never-treated essential hypertension is mainly due to platelet activation. The increased circulating level of PDGF could play a role in the vascular structural changes associated with hypertension.

Acute effects of intravenous sodium chloride load on calcium metabolism and on parathyroid function in patients with primary aldosteronism compared with subjects with essential hypertension

To elucidate the mechanisms involved in increased parathyroid function in primary aldosteronism (PA), we evaluated the effects of an intravenous NaCl load on Ca metabolism and plasma level of intact parathyroid hormone (PTH) in patients with PA compared with that in patients with essential hypertension (EH). Sixteen PA patients and 16 EH patients who were well matched for age, gender, body mass index, renal function, and systolic (SBP) and diastolic blood pressure (DBP) were examined. In each subject, after 6 days of a controlled intake of Na, K, and Ca, isotonic saline was infused at a rate of 500 mL/h for 4 h. At baseline, in spite of similar BP values and urinary Na excretion (U[Na]V), urinary excretion of Ca (U[Ca]V) and PTH were higher in the PA group than in the EH group. In both groups, the NaCl load caused a decrease of serum ionized Ca (Ca2+) and an increase in PTH, U(Na)V, and U(Ca)V. However, these changes were significantly greater in the PA group. The increased baseline U(Ca)V in PA could be due to reduced reabsorption of sodium in aldosterone insensitive tubular sites, as a result of the "escape phenomenon." The increased U(Ca)V may explain the higher basal PTH in PA patients, which is needed for maintaining a normal Ca2+. The greater changes in the Ca2+/PTH profile elicited by the saline load in PA patients are apparently due to a higher calciuretic response following a more exaggerated natriuresis in PA.

Recombinant human ciliary neurotrophic factor alters the threshold of hippocampal pyramidal neuron sensitivity to excitotoxin damage: synergistic effects of monosialogangliosides

Ciliary neurotrophic factor (CNTF) is a multifunctional protein which not only promotes neuronal survival in vitro and in vivo but also controls cell division of neuronal precursors, transmitter differentiation, and glial cell differentiation. Recent studies have indicated that neurotrophic factors can alter hippocampal neuronal threshold to excitotoxin sensitivity. To examine such a role for CNTF, cultures of rat embryonic hippocampal neurons were maintained with recombinant human CNTF for different times, prior to exposure to a toxic dose of glutamate at 5 days in vitro for a further 24 hr. The cytotoxic action of 200 microM glutamate (approximately 40% of pyramidal neurons remaining after 24 hr) was reduced in a concentration-dependent manner in cultures receiving a prior exposure to CNTF within the first 3 days of cell plating: 30 ng/ml CNTF permitted about 75% of the initial number of pyramidal neurons to survive. Presentation of CNTF less than 48 hr before glutamate challenge was ineffective at up to 100 ng/ml. When pyramidal neurons were cultured with a subthreshold concentration (2 ng/ml) of CNTF together with 10 microM of the monosialoganglioside GM1 (or its inner ester form) in the same paradigm, the resulting neuronal survival was similar to that seen with 30 ng/ml CNTF in the face of a glutamate challenge. Such low doses of either CNTF or ganglioside alone were ineffective. The ability of trophic factors to influence the threshold of neuronal sensitivity to excitatory amino acid injury suggests that these proteins could play an important role in the reparative capacity of acutely traumatized central neurons and in neurodegenerative diseases linked to an excitotoxic mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Ganglioside GM1 cooperates with brain-derived neurotrophic factor to protect dopaminergic neurons from 6-hydroxydopamine-induced degeneration

Brain-derived neurotrophic factor (BDNF) has recently been shown to enhance the survival of dopaminergic neurons in cultures derived from the embryonic rat mesencephalon. In the present study BDNF was found to protect cultured dopaminergic neurons from injury induced by acute exposure to the dopaminergic-selective neurotoxin 6-hydroxydopamine. The BDNF effect was concentration (ED50 approximately 10 ng/ml) and time-dependent, as determined by tyrosine hydroxylase immunocytochemistry. More importantly, subthreshold amounts of BDNF were rendered efficacious in the presence of ganglioside GM1: loss of tyrosine hydroxylase positive cells was reduced from 80% to only 20%. Thus GM1 may provide a fruitful treatment strategy for disorders of dopamine function such as Parkinson's disease.

Differences in induction of c-fos transcription by cholera toxin-derived cyclic AMP and Ca2+ signals in astrocytes and 3T3 fibroblasts

The B subunit of cholera toxin, a protein which binds specifically to membrane ganglioside GM1, is known to affect cell growth and differentiation. To investigate the mechanism of these cellular responses at the nuclear level, we used the induction of c-fos in astrocytes and 3T3 fibroblasts as a model. Northern blot analysis showed that treatment with B subunit provokes a rapid and transient expression of c-fos mRNA, independent of a measurable increase in cyclic AMP. The B subunit signal, which is mediated by Ca2+, was compared to cholera toxin and other agents which increase intracellular cyclic AMP levels. In transient transfection assays of astrocytes and fibroblasts, functional analysis of c-fos promoter deletions was used to identify the elements involved in transcriptional activation by B subunit. In astrocytes, the DNA region including the serum response element and the cyclic AMP response element (CRE) are equally required, whereas 3T3 cells require only the CRE for maximal induction. A synergistic effect of signal transduction was mediated by calcium and cyclic AMP on the CRE, being positive in 3T3 cells and negative in astrocytes. Diverse regulatory elements may be thus involved in responses of different cell types to the same extracellular signal. Furthermore, a single regulatory element (CRE) can integrate both calcium and cyclic AMP signals in the control of gene expression.

The complete mature bovine prion protein highly expressed in Escherichia coli: biochemical and structural studies

According to the 'protein only' hypothesis, modification of the 3-dimensional fold of the constituent cellular protein, PrP(C), into the disease-associated isoform, PrP(Sc), is the cause of neurodegenerative diseases in animals and humans. Here we describe the high-level synthesis in Escherichia coli, and purification in the monomeric form, of a histidine-tagged full-length mature PrP (25-249) of bovine brain, termed His-PrP. Based on biochemical and spectroscopic data, His-PrP displays characteristics expected for the PrP(C) isoform. The reported expression system should allow the production of quantities of bovine PrP(C) sufficient to permit 3-dimensional structure determinations.

Heart rate variability in patients with Sjögren's syndrome

Heart rate variability (HRV) gives information about sympathetic parasympathetic autonomic balance. Our purpose was to determine whether HRV is abnormal in patients with Sjögren's syndrome. In 16 patients with Sjögren's syndrome and 30 matched controls, a short time analysis of HRV was performed for both the frequency and the time domain. In the time domain, patients tended to display a slower heart rate, greater R-R variability and higher standard deviation of the mean (SDNN) than did healthy subjects, but the differences were not statistically significant. In the frequency domain the spectral measures of HRV showed a slight reduction of LF and an increase of HF; as a result, the ratio between high and low frequencies, representative of sympathovagal modulation, was significantly reduced. Our data suggest an increase in the parasympathetic control of heart rate in patients with Sjögren's syndrome. This predominance in vagal tone could exert a protective and antiarrhythmic role in patients with primary Sjögren's syndrome, and may be relevant with reference to the lower incidence of sudden death in this disorder compared to other major autoimmune diseases.

Cloning and expression of human ciliary neurotrophic factor

Ciliary neurotrophic factor (CNTF) is a survival factor for avian ciliary ganglion neurons and a variety of other neuronal cell types in vitro. We report here the cloning of the entire genomic sequence encoding human CNTF and its primary structure. Biologically active CNTF has been expressed in Chinese hamster ovary cells from a human genomic DNA clone. Human CNTF has no significant sequence similarity to any previously reported protein, although approximately 84% similarity exists compared with rat and rabbit CNTF. The lack of both an N-terminal signal sequence and consensus sequences for glycosylation or hydrophobic regions, and the fact that active CNTF is expressed but not released into the culture medium of transfected cells, argue in favour of human CNTF as a cytosolic protein. These data provide a basis for understanding the role of CNTF in nervous system physiology and pathology.

Recombinant human TIMP-3 from Escherichia coli: synthesis, refolding, physico-chemical and functional insights

Matrix metalloproteinases are inhibited by a growing family of specific tissue inhibitors, TIMPs. The cDNA of the third member of the family, TIMP-3, was obtained by using a reverse transcription-polymerase chain reaction (RT-PCR) to amplify the corresponding mRNA from human placenta. Cloning and expression of the TIMP-3 were performed in Escherichia coli as a fusion protein with a 36 amino acid N-tail containing a His cluster. In the host vector system, rhTIMP-3 was stored intracellularly in its denatured, insoluble form in inclusion bodies. Slow dilution of denaturing and reducing agents, from rhTIMP-3 His bound to a metal affinity solid phase, was followed by partial acid removal of the N-tail, which leaves a residue of four amino acids. Circular dichroism, fluorescence and second-derivative UV spectroscopic analyses supported correct refolding of the recombinant and zymography showed inhibition of both MMP-2 and MMP-9 gelatinolytic activities. The role of the C-terminus, which has closer homology with TIMP-2 than TIMP-1, was also investigated: a C-truncated mutant, similarly cloned and expressed in E. coli, shows complete lack of inhibitory activity on MMP-9, still retaining some on MMP-2. The described protein engineering shows high yield of active inhibitor, unglycosylated as in the native form.

Nerve growth factor (NGF) receptors in a central nervous system glial cell line: upregulation by NGF and brain-derived neurotrophic factor

The neurotrophic proteins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are related in their primary amino acid structures. In this study we investigated the extent to which the low-affinity NGF receptor (LNGFR) in C6 glioma cells can discriminate between the neurotrophins NGF and BDNF. LNGFR-immunoreactivity (IR) was studied in C6 cells treated for 16 hr with NGF (50 ng/ml) or BDNF (10 ng/ml), using immunogold labelling and electron microscopic morphometric analysis. The cells were exposed to the anti-NGFR antibody 192-IgG, followed by immunoglobulin conjugated with colloidal gold. Untreated C6 cells exhibited some surface gold label (positive LNGFR-IR). Cells treated with NGF or BDNF displayed significantly increased LNGFR-IR on all surfaces in terms of gold labeling, which was more pronounced in NGF-treated cells. LNGFR-IR was also localized in coated endocytotic vesicles, in smooth endoplasmic reticulum, and in secondary multivesicular lysosomes in neurotrophin-treated and untreated cells. The increase in LNGFR protein was further substantiated by a correspondingly higher content of LNGFR mRNA detected after 15 hr of either NGF or BDNF treatment. These results suggest that the LNGFR in glial cells can be upregulated by the structurally related neurotrophins NGF and BDNF.